<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <div id="app">
        <button v-on:click="fn">click me</button>
        <button @mousedown="fn">click me2</button>
    </div>
</body>
<script src="./js/vue.js"></script>
<script>
    Vue.config.productionTip = false


    new Vue({
        el:"#app",
        data:{
            msg:"123"
        },
        methods:{
            fn(){
                console.log("fn",this.msg)
            }
        }
    })
</script>
</html>